Factors affecting bone mineral density in postmenopausal women

This study aimed to determine the relationship between bone mineral density (BMD) and demographic, biochemical, and clinical features according to BMD measurement sites. The results indicated that BMD correlates negatively with menopause duration, parity, and history of fractures but positively correlates with obesity, physical activity, education, and serum ferritin. Purpose/Introduction Osteoporosis (OP) is an important cause of morbidity and mortality in the elderly people. The impacts of various factors on bone mineral density (BMD) differ across diverse population. We hypothesized that the influences of factors which affect BMD vary according to BMD measurement sites. The aim of this study was to determine the relationship between BMD in the femoral neck (FN) and lumbar spine (LS) with some common clinical, demographic, and biochemical parameters in postmenopausal women. Methods In this cross-sectional case-control study, all postmenopausal women of the Amirkola Health and Ageing Project (AHAP) who performed bone densitometry were included. BMD at FN and LS was measured by DXA method. Data regarding clinical, demographic, and biochemical characteristics were provided. OP was diagnosed by the International Society for Clinical Densitometry criteria. Pearson correlation and multivariate regression analyses with simultaneous adjustment were performed to determine relationship. Results Five hundred thirty-seven women with mean age of 67.9 +/- 6.7 years and mean menopause duration (MD) of 15.8 +/- 5.1 years were studied. MD correlated negatively with FNBMD and LS-BMD g/cm(2) (r=-0.405, p=0.001 and r=-0.217, p=0.001). Body mass index (BMI) correlated positively with FN and LS-BMD g/cm(2) (r=0.397, p=0.001 and r=0.311, p=0.001). The association of MD with risk of FN-OP was stronger than LS-OP. Obesity and metabolic syndrome (MS) and higher serum ferritin reduced the risk of OP at both LS and FN similarly, whereas the impacts of parity, prior fracture, high level of education, and physical activity were significantly different across BMD measurement sites. Conclusion The results of this study indicated a significant association between OP and MD, obesity, parity, MS, history of fracture, serum ferritin, level of education, and physical activity. However, the direction and the strength of association varied across BMD measurement sites.